Conventionally, a reproduction method called random reproduction has been widely used in the field. With this reproduction method, on completing reproducing operation of a current music program using a CD (Compact Disc) player, the next music program to be reproduced is randomly selected from all music programs except those already being reproduced. After searching the next music program, reproducing operation of the next music program starts.
Referring to FIG. 9, a configuration of a generally used CD player will be described hereinbelow.
The CD player comprises: an optical pickup 31 for reading out information from a disk (not shown); a servo circuit 32 for respectively controlling a focus servo for converging a laser beam, for reading out the information, on the disk, a tracking servo for improving an act of following of a laser beam from the optical pickup 31 in order to read out the information, a spin servo for rotating the disk, a slide servo for moving the optical pickup 31 over the disk from an inner portion toward an outer portion or from the outer portion toward the inner portion; a microcomputer 33 for controlling the servo circuit 32, a signal processing circuit 35 (to be described later) and output of display use data to a display 40 based on input from an operation unit 38 (to be described later) and for performing other controls; the signal processing circuit 35 which modulates output signals from the optical pickup 31 in the form of EFM (Eight to Fourteen Modulation) and demodulates in the form of error-correcting subcode; a D/A converter 36 for converting digital output signals from the signal processing circuit 35 into analog signals; an audio AMP 37 for amplifying output from the D/A converter 36; a drive circuit 34 for performing focus control, tracking control, slide motor control and spin motor control of the optical pickup 31 based on input signals from the servo circuit 32 or the signal processing circuit 35; random music program selection means 39 for randomly selecting the next music program to be reproduced; and the display 40 for showing the display use data. In addition, the operation unit 38 includes a random reproduction key 38a for instructing the random reproduction and a stop key 38b for terminating the random reproduction.
The conventional random reproduction method, which has been widely used, will be described hereinbelow referring to a flow chart in FIG. 7.
A system is first to be initialized. Then, after loading a disk, reading out of TOC (Table of Contents) information recorded on the disk starts (S1). The TOC information is stored on an inner portion of the disk and it contains information regarding at least starting and ending positions of the respective music programs recorded on the disk.
The random reproduction key 38a (see FIG. 9) for instructing the random reproduction of the music programs is next to be operated (S2). This S2 is a step for starting up the random reproduction. Then, the random music program selection means 39 (see FIG. 9) selects the next music program to be reproduced (S3). Here, the system is designed such that each music program is to be reproduced only once.
Then it is judged whether the reproduction of all the music programs has been completed. If there are no music programs left to be reproduced, the sequence moves to S8 (to be described later) to terminate the random reproduction. On the other hand, if there are any music programs left to be reproduced, the sequence goes on to S5 (S4).
In S5, a searching operation is performed of the next music program to be reproduced. Here, the time required for searching varies depending on a distance between a present position of the pickup and a starting position of the next music program to be reproduced, in short, the greater the distance, the longer the search time.
After the searching operation in S5 has been completed, the reproduction of the searched music program starts (S6). Then, on completing the reproduction of the music program, it is checked whether the stop key is operated (S7). If the stop key is operated in S7, the sequence moves to S8 to terminate the random reproduction. If not, on the other hand, the sequence goes back to S3 to repeat the above-mentioned process so as to continue the reproducing operation.
Now assuming that fifteen (15) music programs are recorded on the disk (recorded in areas indicated by TNO=1 to TNO=15 on the disk in FIG. 8), the following will discuss a search method when the random reproduction is performed using the generally used CD player referring to FIG. 8.
As shown in FIG. 8, in the figure, a search time indicated by an arrow (1) (the search of a music program recorded in TNO=2 from TOC area) is, for example, 0.7 second. Similarly, a search time indicated by an arrow (2) (the search of a music program recorded in TNO=4 from TNO 2) is, for example, 0.7 second. Respective time required for search (3), search (4), search (5) and search (6) are 1.5 seconds, 0.5 second, 1.1 seconds and 3.3 seconds. Here, the time required for the search (4) is the shortest (0.5 second) and that for the search (6) is the longest (3.3 seconds) among all. As can be seen from this example, the time required for searching is not constant.
Thus, as described above, when performing the random reproduction with the conventional method, a time interval is not constant between an end of a current music program and a beginning of the next music program to be reproduced. Therefore, a waiting time for the next music program is not likely to be constant. For this reason, listeners may not feel comfortable.
Further, this conventional method presents a problem that it is not applicable to the case where information recorded on a disk is to be reproduced at a constant interval (for example, the Hundred Poems by the Hundred Poets for a Japanese card game).